Share this story

Isaac Asimov dubbed neutrinos "ghost particles." John Updike immortalized them in verse. They've been the subject of several Nobel Prize citations, because these weird tiny particles just keep surprising physicists. And now we have a much better idea of the upper limit of what their rest mass could be, thanks to the first results from the Karlsruhe Tritium Neutrino experiment (KATRIN) in Germany. Leaders from the experiment announced their results last week at a scientific conference in Japan and posted a preprint to the physics arXiv.

"Knowing the mass of the neutrino will allow scientists to answer fundamental questions in cosmology, astrophysics, and particle physics, such as how the universe evolved or what physics exists beyond the Standard Model," said Hamish Robertson, a KATRIN scientist and professor emeritus of physics at the University of Washington. "These findings by the KATRIN collaboration reduce the previous mass range for the neutrino by a factor of two, place more stringent criteria on what the neutrino's mass actually is, and provide a path forward to measure its value definitively."

The ghostly particles are devilishly hard to detect because they so rarely interact with other particles, and when they do, they only interact via the weak nuclear force. Most neutrino hunters bury their experiments deep underground, the better to cancel out noisy interference from other sources, notably the cosmic rays continually bombarding Earth's atmosphere. The experiments usually require enormous tanks of liquid—dry-cleaning fluid, water, heavy water, mineral oil, chlorine, or gallium, for example, depending on the experimental setup. This increases the chances of a neutrino striking one of the atoms in the medium of choice, triggering the decay process. The atom changes into a different element, emitting an electron in the process, which can be detected.

Neutrinos were first proposed by Wolfgang Pauli in a 1930 letter to colleagues. He was trying to explain some baffling experimental results on radioactive beta decay in atomic nuclei, where energy appeared to be missing—something he deemed (correctly) to be impossible. He thought a new kind of subatomic particle with no charge and no mass may have carried away the missing energy; it was Enrico Fermi who later dubbed it a neutrino.

Clyde Cowan and Frederick Reines were the first to observe these ghostly particles in 1956, thanks to the fusion reactions in nuclear power plants that proliferated after World War II. Ten years later, physicists detected the first solar neutrinos from the Sun. This snagged Ray Davis Jr. and Masatoshi Koshiba a Nobel Prize in 2002, shared with Riccardo Giacconi (who was honored "for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources").

The only problem was that there were far fewer solar neutrinos being detected than predicted by theory, a conundrum that became known as the solar neutrino problem. In 1962, physicists discovered a second type ("flavor") of neutrino, the muon neutrino. This was followed by the discovery of a third flavor, the tau neutrino, in 2000.

By then, physicists already suspected that neutrinos might be able to switch from one flavor to another, thanks in large part to 1998 observations by Japan's Super-Kamiokande collaboration (Super-K). In 2002, scientists at the Sudbury Neutrino Observatory (or SNO) announced they had solved the solar neutrino problem. The missing solar (electron) neutrinos were just in disguise, having changed into a different flavor on the long journey between the Sun and the Earth. Arthur B. McDonald of SNO and Takaaki Kajita of Super-K shared the 2015 Nobel Prize in Physics for their respective breakthroughs.

If neutrinos oscillate, then they must have a teensy bit of mass after all. As Adrian Cho explained in a 2016 article for Science, "Were neutrinos massless, they would have to move at light speed, at least in a vacuum, according to Einstein's theory of relativity. If that were the case, time for them would stand still, and change would be impossible."

But determining precisely what that mass is constitutes another knotty neutrino-related problem. There are three neutrino flavors, but none of them has a well-defined mass. Rather, different kinds of "mass states" mix together in various ways to produce electron, muon, and tau neutrinos. That's quantum weirdness for you.

Enlarge/ The layout and major features of the KATRIN experimental facility at the Karlsruhe Institute of Technology.

Karlsruhe Institute of Technology

KATRIN's new results placing an upper limit for neutrino mass actually applies to the average of all three masses. The lower bound is 0.02 eV (electron volts); neutrinos can't have a lower mass than that. And KATRIN's data suggests they can't weigh more than 1 eV—or 1/500,000th of the mass of the electron.

The experiment uses tritium (a highly radioactive isotope of hydrogen, with one proton and two neutrons) to generate electron-neutrino pairs: an electron and a neutrino that share 18,650 eV of energy between them. Usually that energy is divided equally, but there are rare pairs—just a fraction of the roughly 25 billion electron-neutrino pairs produced every second—where the electron hogs nearly all of it, so there's only a tiny amount left for the neutrino. Those pairs are the focus of KATRIN scientists. They can't measure the neutrinos directly, so instead they subtract the electron's energy to deduce that of the neutrino and, hence, its mass (because E=mc2).

These preliminary results are based on just 28 days of data, so it doesn't constitute a definitive measurement yet; more data is needed. But it's already half the previous estimate of what physicists thought the upper limit on mass would be, and the actual value could be lower still. Or neutrinos could throw physicists another curveball and the additional data will yield a higher upper limit.

The experiment could also shed light on the possible existence of an exotic fourth type of neutrino, dubbed the "sterile" neutrino, that doesn't interact with regular matter at all, apart from, perhaps, its fellow neutrinos. That would have big implications for the nature of dark matter, although despite a tantalizing hint in 2018, sterile neutrinos have thus far proven elusive.

"There is indirect evidence that the neutrino masses are smaller than what KATRIN taught us last week," André de Gouvêa, a theoretical physicist at Northwestern University who was not involved in the measurement, told Scientific American. “The indirect evidence does not replace what KATRIN can do, however, so the result in itself is very significant. Perhaps more important is that KATRIN demonstrated that things are working and that they appear to be on track to reach much further."

90 Reader Comments

As Adrian Cho explained in a 2016 article for Science, "Were neutrinos massless, they would have to move at light speed, at least in a vacuum, according to Einstein's theory of relativity. If that were the case, time for them would stand still, and change would be impossible."

I don't get the leap of faith here. Even if neutrinos couldn't 'oscillate' internally because time stands still for them at light-speed, they could still potentially interact with each other or with some other dark matter particle (just like photons can interact with matter), which could result in changes to their properties (just like photons can be deflected, absorbed/re-emitted, interfered with...) Why are all such possibilities being seemingly dismissed out-of-hand?

If neutrinos interacted more often than almost never, then we would be able to experiment on them more easily. However, it takes a planetary mass to cause even a small percentage of high energy solar neutrinos to oscillate. And it takes a solar mass to create sufficient electron density that weak interactions with neutrinos can be observed:

They can't measure the neutrinos directly, so instead they subtract the electron's energy to deduce that of the neutrino and, hence, its mass (because E=mc2).

Wouldn't the 'missing' energy be divided between the neutrino's mass and its kinetic energy (i.e. its rest mass times the square of whatever speed it's moving at relative to the observer)? How do we know where that ratio is, for such measurements: since neutrinos have mass, they could theoretically move at any speed less than c, including at 0 m/s or at 0.99999c. That's a big range, and a huge intrinsic uncertainty for the measurement, isn't it?

Yes, the missing energy is divided between the neutrino's rest mass and kinetic energy. The thing is, neutrinos are so light that it only takes a small amount of energy to boost them to relativistic speeds-- far less energy than it takes to produce them.

The so-called "relic neutrinos" originally created from the Big Bang are likely moving at around 0.01 c, but it took almost 20 billion years for them to slow down from 0.99+ c.

You were doing really well up to the 20 billion years to slow down right at the end. Maybe you are looking for simply the current age of the Universe, not some future one?

Clyde Cowan and Frederick Reines were the first to observe these ghostly particles in 1956, thanks to the fusion reactions in nuclear power plants that proliferated after World War II.

I think you meant fission.

Quote:

KATRIN's new results placing an upper limit for neutrino mass actually applies to the average of all three masses. The lower bound is 0.02 eV (electron volts); neutrinos can't have a lower mass than that.

The sad thing is, the UK was on the cutting edge of this with the Neutrino Factory. Then the tories came in and gutted the funding for it at the RAL. Many Ars-ians even worked indirectly on it, with the Muon1 DPAD [Distributed particle accelerator design] project, which, yes, was part of the Neutrino factory, helping design the Muon channel (the accelerator went proton beam to tantalum or titanium rod, which gave off pions, that decayed to muons, that decayed to mu-neutrinos. which would go into a cooling ring, before being fired at detectors locally (to RAL, in Oxfordshire), Italy and Japan.

we were a good way in, but the tory austerity knows no bounds.

For the last 6 years, the lead scientist on it has been at Brookhaven National Lab in Long Island, as the NF project was mothballed at RAL and Daresbury.

(Disclaimer, I not only worked on this project for 14 years, as a beta tester, manual designer, and Muon1 press guy, the guy in charge of the NF turned out to be the dad of a friend from school - small world.)

But thanks to that austerity the UK now has the surplus cash to splurge on a bridge from Scotland to Ireland, or high speed rail for Leeds, or a new airport on an island in the Thames Estuary, or to pay for 1,000 more columns from Boris in the "Telegraph". So your sacrifice has not been in vain!

I read the headline, I looked at the picture and the first thing I thought was Hitchhikers Guide to the galaxy and that was a vogon ship....

When I realized it was a real picture the next thought was...no way they got that through town, but I guess they did.

Cool Article.

++

I'm guessing the "how are we going to get that thing from where it was built to where it will operate" was the LAST thing they actually considered. Followed by a bunch of swearing in German. Glad they figured it out though.

Don't bet on it. German engineers are known for nailing down the details before they start a project, and they knew this thing would have extremely special transportation needs. I recall a story on how Airbus worked out the details of how they were going to transport parts of the A380 through villages. They considered clearances, loads, overhead cables, and other things before they started building the big parts.

They kinda winged it. They made sure that the Tank was liftable by a crane and that it would fit on a flatbed transporter and a barge. They worked out the details at a later date...

No, it was famously one of his hobbies: Whenever Asimov had some spare time, he would go out into the countryside and neutrino some ghost particles. Most successful ghost particle neutrioner there was, really.

I read the headline, I looked at the picture and the first thing I thought was Hitchhikers Guide to the galaxy and that was a vogon ship....

When I realized it was a real picture the next thought was...no way they got that through town, but I guess they did.

Cool Article.

++

I'm guessing the "how are we going to get that thing from where it was built to where it will operate" was the LAST thing they actually considered. Followed by a bunch of swearing in German. Glad they figured it out though.

To be fair almost nobody thinks about delivery of equipment until after stuff is on order and ready to ship.

German engineers are known for nailing down the details before they start a project, and they knew this thing would have extremely special transportation needs. I recall a story on how Airbus worked out the details of how they were going to transport parts of the A380 through villages. They considered clearances, loads, overhead cables, and other things before they started building the big parts.

There is tradition to that... I visited Limburg a few weeks ago, a pittoresque town on an old trade road between Cologne and Frankfurt. On a narrow passage between two medieval houses, I saw a sign explaining that there was a corresponding mark at a city gate in Cologne. It told traders whether their cart would pass through the Limburg bottleneck and reach Frankfurt - or not...

I know I'm probably being over-pedantic but the really big problem with beta decay wasn't the variation in energy. At the time, nobody could measure accurately enough to be sure that this wasn't just a feature of that decay. The problem, which was easy to spot, was momentum. The nucleus and the electron did not travel in opposite directions with net zero momentum, they did the unthinkable and moved in directions with an included angle less than 180 degrees. Some physicists even started to wonder whether the conservation of energy applied at the quantum level.It then took nearly half a century to verify the existence of the postulated neutrinos, which is comparable to the time between postulation and demonstration of the Higgs.It must be a great encouragement to theoretical physicists that you might have retired before your speculation is proven true or false.

I think it's getting far easier and more logical to assume we are living in a simulation than to try and make sense of how we think things work in this "universe".

William of Ockham wants a word with you.It is exactly the same fallacy as postulating the existence of a creator deity - the thing running the simulation or creating the universe must be bigger and more complex than the universe, so what created the simulator?

I think it's getting far easier and more logical to assume we are living in a simulation than to try and make sense of how we think things work in this "universe".

William of Ockham wants a word with you.It is exactly the same fallacy as postulating the existence of a creator deity - the thing running the simulation or creating the universe must be bigger and more complex than the universe, so what created the simulator?

I though it would have been easier to acknowledge that we don't know everything...long before going to "simulation". Is our ignorance, as a species whose scientific investigation began incredibly late in our development, really that much of a mystery?

The title of this article is incorrect. Cosmological constraints place significantly tighter bounds on the sum of neutrino masses. The most recent paper by the Planck collaboration places the upper bound of the sum of neutrino masses at < 0.17 eV see P.A.R. Ade et al., [Planck Collab.], Astron. Astrophys. 594, A13 (2016).

This measurement is just an improvement over direct kinetic measurements of the neutrino mass. The cosmological measurements rely on modeling the effect neutrino mass has on the Cosmic Microwave Background and Baryon Acoustic Oscillations and then comparing measurements of the universe to theory.

There is a trend in the particle physics community to ignore cosmological constraints on fundamental physics because of a lack of understanding of the methodology of cosmologists. Their work gets dismissed as "model dependent". For an example of this, read the abstract of the Katrin paper discussed in this article.

To be a little catty, the title should read "Particle physicists place a constraint that's 10 times worse than cosmologists, but at least they didn't have to learn differential geometry"

It is true, the KATRIN limit is way worse than cosmological limits, and even 5 years later when they take enough data to get their target sensitivity they'll only be *comparable* to cosmological limits, so it is entirely possible and not even unlikely that KATRIN will never actually measure the neutrino mass without significant hardware upgrades.

Part of the rant is incorrect though. The real value of KATRIN is indeed that it is independent of cosmology, and hence offers a more direct measurement that's less model-dependent. There are ways for theorists to wriggle around a cosmological limit. There are a lot less ways to wriggle around a direct limit/measurement. It's not that particle physicists don't understand; it's that alternative models of cosmology can potentially be proposed to get around cosmological measurements.

Plus, the previous poster/ranter forgot that KATRIN was quite delayed from its original schedule, and it was actually supposed to set the best limit back when it was conceived. It is unlikely for that to happen with current hardware now, but it's been over a decade and technological improvements may very well mean they could improve on the cosmological limits with some hardware upgrades. It's unfortunate but man I'm glad I don't have to be a grad student working on that experiment.

I think it's getting far easier and more logical to assume we are living in a simulation than to try and make sense of how we think things work in this "universe".

William of Ockham wants a word with you.It is exactly the same fallacy as postulating the existence of a creator deity - the thing running the simulation or creating the universe must be bigger and more complex than the universe, so what created the simulator?

generate electron-neutrino pairs: an electron and a neutrino that share 18,650 eV of energy between them. Usually that energy is divided equally

I'm a little confused by this. If the typical case for an electron-neutrio pair is having the energy divided equally then how is the upper limit on neutrino mass 1eV? Is this a slight misnomer? Are there actually many neutrino's for each electron?

Is the rest mass of the neutrino between 0.2-1eV and they can actually have much more energy or something?

"Clyde Cowan and Frederick Reines were the first to observe these ghostly particles in 1956, thanks to the fusion reactions in nuclear power plants that proliferated after World War II. "

bolding mine

Wrong reaction? Are these Physicists holding out on us? Or are their nuclear reactions in fission plants that go the other way?

Ninja'd by dmslev

There has been research reactors for fusion since around the 1940s, but as they take more power to make work than they generate and have some other issues are not yet a viable source of commercial power

generate electron-neutrino pairs: an electron and a neutrino that share 18,650 eV of energy between them. Usually that energy is divided equally

I'm a little confused by this. If the typical case for an electron-neutrio pair is having the energy divided equally then how is the upper limit on neutrino mass 1eV? Is this a slight misnomer? Are there actually many neutrino's for each electron?

Is the rest mass of the neutrino between 0.2-1eV and they can actually have much more energy or something?

Mass is not the energy of the particle. The confusion is becasue they are both measured in the same units. eV are used for mass in this case becasue it's far easier to write then kg or atomic mass units because the vale is so small. 1eV or 1x10-9 amu

I think it's interesting that the lower bound on neutrino mass is comparable to kT at room temperature.

Is anyone doing research with cryogenic tritium?

Why? Temperature has virtually zero effect on radioactive decomposition. That's why half-lives do not include a temperature component.[edit -I now see the point which is that the momentum of the components includes a term for the original momentum of the nucleus, in the lab frame of reference. But it is small.]

Incidentally the article is wrong about tritium. The curve of electron energy versus frequency peaks at around 3keV, and has an average of around 6 keV. The decay energy is around 18.6keV.Most of the energy is not clustered around 9.3keV.

This makes tritium decay particularly interesting because most of the energy is normally taken away by the neutrino.

It also means that tritium is harmless unless you inhale or drink it, as the electrons can't penetrate skin. It's why tritium compounds were used for a while in beta-lights, till LEDs obsoleted them and waste disposal became an issue. There are not many short half life radioisotopes which were once sold in readily available commercial products containing about 20Ci.

generate electron-neutrino pairs: an electron and a neutrino that share 18,650 eV of energy between them. Usually that energy is divided equally

I'm a little confused by this. If the typical case for an electron-neutrio pair is having the energy divided equally then how is the upper limit on neutrino mass 1eV? Is this a slight misnomer? Are there actually many neutrino's for each electron?

Is the rest mass of the neutrino between 0.2-1eV and they can actually have much more energy or something?

The article is quite wrong, see my post above.If a tritium atom produces an 18.6keV electron, the neutrino energy is very low. Remember that the decay energy is split between the neutrino kinetic energy and its mass.

I think it's getting far easier and more logical to assume we are living in a simulation than to try and make sense of how we think things work in this "universe".

Easier? Well, yeah. If we all took the easy way, we'd still be living in caves. Logical? No. Because the 'We're living in a simulation!' nonsense is just another version of 'God did it'. If the universe were a simulation, you saying it's a simulation would be part of the simulation. Stop trying to take the easy way out. 'We do these things not because they are easy but because they are hard.' You insult the hard work and effort that people in the last few hundred years have done to show us how this place works. Either help continue that work or get out of the fucking way. We've had people like you holding us back for too long. We don't need you and your lazy excuse for 'thinking'.

Well, that figures. There are people who don't care how the universe works. Those people are called morons. They just think it works because of magic or some god. Thankfully, most morons aren't clever enough to fuck up the rest of us who know that finding out how this place works keeps us alive. Just stand back and don't drool on anyone.

I think it's interesting that the lower bound on neutrino mass is comparable to kT at room temperature.

Is anyone doing research with cryogenic tritium?

Why? Temperature has virtually zero effect on radioactive decomposition. That's why half-;lives do not include a temperature component.

It doesn't affect the rate of decay, but it certainly affects kinetic energy of the tritium nucleus.

Unless you don't believe in conservation of energy, it also has an equal effect on the total kinetic energy of the products.

Thermal energy alone (at room temperature) is the difference between an "at rest" neutrino and one moving at relativistic velocities, if the mass is closer to the lower bound. It's still a significant factor at the upper bound.

I think it's getting far easier and more logical to assume we are living in a simulation than to try and make sense of how we think things work in this "universe".

William of Ockham wants a word with you.It is exactly the same fallacy as postulating the existence of a creator deity - the thing running the simulation or creating the universe must be bigger and more complex than the universe, so what created the simulator?

We were designed to lack the level of intelligence necessary to answer that question, obviously. Can’t have the inmates running the asylum, after all.

I think it's interesting that the lower bound on neutrino mass is comparable to kT at room temperature.

Is anyone doing research with cryogenic tritium?

Why? Temperature has virtually zero effect on radioactive decomposition. That's why half-;lives do not include a temperature component.

Incidentally the article is wrong about tritium. The curve of electron energy versus frequency peaks at around 3keV, and has an average of around 6 keV. The decay energy is around 18.6keV.Most of the energy is not clustered around 9.3keV.

This makes tritium decay particularly interesting because most of the energy is normally taken away by the neutrino.

It also means that tritium is harmless unless you inhale or drink it, as the electrons can't penetrate skin. It's why tritium compounds were used for a while in beta-lights, till LEDs obsoleted them and waste disposal became an issue. There are not many short half life radioisotopes which were once sold in readily available commercial products containing about 20Ci.

He's *kinda* right. The temperature matters because the kinetic energy of the originating atoms (and hence temperature) does smear out the beta spectrum a tiny bit. It doesn't matter yet, however, because the amount of kinetic transferred to the beta particle is going to be 1/2000 of kT (order of magnitude) due simple kinematics and reduced mass considerations, so other sources of error dominate.

I think it's interesting that the lower bound on neutrino mass is comparable to kT at room temperature.

Is anyone doing research with cryogenic tritium?

Why? Temperature has virtually zero effect on radioactive decomposition. That's why half-;lives do not include a temperature component.

Incidentally the article is wrong about tritium. The curve of electron energy versus frequency peaks at around 3keV, and has an average of around 6 keV. The decay energy is around 18.6keV.Most of the energy is not clustered around 9.3keV.

This makes tritium decay particularly interesting because most of the energy is normally taken away by the neutrino.

It also means that tritium is harmless unless you inhale or drink it, as the electrons can't penetrate skin. It's why tritium compounds were used for a while in beta-lights, till LEDs obsoleted them and waste disposal became an issue. There are not many short half life radioisotopes which were once sold in readily available commercial products containing about 20Ci.

He's *kinda* right. The temperature matters because the kinetic energy of the originating atoms (and hence temperature) does smear out the beta spectrum a tiny bit. It doesn't matter yet, however, because the amount of kinetic transferred to the beta particle is going to be 1/2000 of kT (order of magnitude) due simple kinematics and reduced mass considerations, so other sources of error dominate.

I think it's getting far easier and more logical to assume we are living in a simulation than to try and make sense of how we think things work in this "universe".

Easier? Well, yeah. If we all took the easy way, we'd still be living in caves. Logical? No. Because the 'We're living in a simulation!' nonsense is just another version of 'God did it'. If the universe were a simulation, you saying it's a simulation would be part of the simulation. Stop trying to take the easy way out. 'We do these things not because they are easy but because they are hard.' You insult the hard work and effort that people in the last few hundred years have done to show us how this place works. Either help continue that work or get out of the fucking way. We've had people like you holding us back for too long. We don't need you and your lazy excuse for 'thinking'.

I think it's getting far easier and more logical to assume we are living in a simulation than to try and make sense of how we think things work in this "universe".

William of Ockham wants a word with you.It is exactly the same fallacy as postulating the existence of a creator deity - the thing running the simulation or creating the universe must be bigger and more complex than the universe, so what created the simulator?

The experiment uses tritium (a highly radioactive isotope of hydrogen, with one proton and two neutrons) to generate electron-neutrino pairs

Mix some of that ³H with some of that thing called oxygen to get super heavy water, the kind that will kill you from your insidey bits if you consume it while being mostly harmless to your outsidey bits (dead skin and air are good at blocking beta particles emitted from the beta decay).

As someone who has been responsible for the deliberate creation of tritium oxide, can I be a bit more nuanced?

You actually need quite a high dose of tritium to do serious harm. I believe people have long term survived inhaling 20Ci of the gas, and the official treatment for accidentally ingesting tritium oxide is to spend several days drinking lots of water. It tends not to hang around in the body. I need perhaps hardly add that you are not likely to drink pure tritium oxide, as it boils through self heating long before that concentration is reached.

Some years ago I was talking to a visiting French chemist about chemical hazards and remarked that on an early lab inspection after I took it over I had discovered some equipment that contained glass mercury switches - with no protection in case of breakage, terrifying things. "Yes," he remarked, "Mercury, cadmium, these worry me. A few Curies of tritium, no problem."

Actually no. Fossil FUD aside, there is no evidence of any human ever having been harmed, let alone killed, by tritiated water.

Tritium is not "highly" radioactive.)

Indeed, tritium is more likely to harm you through its biochemistry than through its radioactivity.

Lots of enzymes that catalyze reactions that involve water molecules get pretty screwed up by heavy (deuterated or tritiated) water if it is present at significant concentrations. As far as these enzymes (that evolved to work in just plain water water) are concerned, the mass is wrong, the volume is wrong, the dipole moment is wrong, it's all just wrong...it makes them grumpy and that makes them start doing silly things.

Lots of enzymes that catalyze reactions that involve water molecules get pretty screwed up by heavy (deuterated or tritiated) water if it is present at significant concentrations. As far as these enzymes (that evolved to work in just plain water water) are concerned, the mass is wrong, the volume is wrong, the dipole moment is wrong, it's all just wrong...it makes them grumpy and that makes them start doing silly things.

The notion that enzymes could be grumpy makes me wonder if they become upset when anthropomorphized?

Also, point of order with regard to the dipole moment of water versus heavy water:

Lots of enzymes that catalyze reactions that involve water molecules get pretty screwed up by heavy (deuterated or tritiated) water if it is present at significant concentrations. As far as these enzymes (that evolved to work in just plain water water) are concerned, the mass is wrong, the volume is wrong, the dipole moment is wrong, it's all just wrong...it makes them grumpy and that makes them start doing silly things.

The notion that enzymes could be grumpy makes me wonder if they become upset when anthropomorphized?

Also, point of order with regard to the dipole moment of water versus heavy water:

I have to say that it would be difficult to get "significant concentrations" of tritium oxide in the body. I quote:"Fukishima...[]...This identified that the March 2016 holding of tritium on-site was 760 TBq (equivalent to 2.1 g of tritium or 14 mL of tritiated water) in a total of 860,000 m3 of stored water."

For old farts like me, there's about 28 Ci in a TBq, so that's very roughly 30 000 Ci.I leave you to work out the concentration that a radiologically unpleasant dose of 30 Ci would reach in body water, but I would be surprised if it was high enough to affect enzyme biochemistry directly rather than by firing electrons at things.